Steering columns are known which, in order to increase the occupant safety in the event of a vehicle collision, what is referred to as a crash situation, comprise what is referred to as a crash device or a crash system. A crash device of this type makes provision for the adjusting unit, to which the steering wheel is attached on the driver's side, to be displaceable forward in the longitudinal direction, i.e. in the direction of travel, relative to the body-mounted supporting unit of the steering column. If the driver's body impacts at a high speed against the steering wheel during a head-on collision, a relatively large force is exerted on the steering wheel in the longitudinal direction, said force exceeding a limit value which only occurs in a crash situation. In order to reduce the risk of injury in this case by means of a controlled and as uniform as possible a retardation of the body striking against the steering wheel, it is known to couple an energy absorption device between the supporting unit and the adjusting unit. Said energy absorption device comprises an energy absorption element which is fastened via first and second fastening elements firstly to a body-mounted component of a supporting device, for example a bracket unit or a holding clamp held on the bracket unit, and secondly to a component which is displaceable together with the steering wheel relative to the body in the crash situation, for example the adjusting unit, a sleeve unit or the like. The fastening elements are connected to each other via at least one deformation element which is located in the force flux between the fastening elements during the relative movement of the fastening elements. As a result, in the crash situation, the energy which is introduced over the displacement distance of the relative movement is converted into a defined plastic deformation of the deformation element, and therefore a controlled, moderated retardation takes place.
In the prior art, an energy absorption device for a steering column is described in DE 10 2013 104 958 B3 which is taken as the basis of the generic type. The deformation element provided here is a bending tab which, in the crash situation, is continuously bent over the displacement distance between the sleeve unit of an adjusting unit and a holding unit and therefore ensures a moderated retardation by means of continuous energy absorption during the deformation of the bending tab. For energy absorption, DE 1 962 183 discloses an energy absorption device with a deformation element which is designed as a bending and tearing tab. This basically involves a bending tab which, during bending, is additionally severed along a defined tearing line from a support, as a result of which energy is additionally absorbed. The bending and tearing tab is likewise bent over continuously over the displacement distance during a relative movement of sleeve unit and holding unit.
An advantage of the known energy absorption devices is the energy absorption, which is uniform over the displacement distance, by the deformation element. However, it is disadvantageous that the deformation element may already be deformed outside the crash situation, for example due to an action of force due to unauthorized use on the steering wheel or an inadvertent excessive application of force when adjusting the steering column, and this may impair the effectiveness of the crash device in the crash situation. In order to prevent this, it has indeed already been proposed, for example in DE 196 37 176 A1, in addition to the frictional connection between the body and the steering column components which are displaceable relative thereto, to insert a capsule having tear-off pins which only tear off in the crash situation and only then release the force flux via the deformation element. However, the known arrangement is disadvantageous in that not only does the energy absorption element have to be provided and mounted together with its fastening elements, but in addition the capsule and the tear-off pins have to be manufactured, provided and mounted. This gives rise to a higher outlay on manufacturing, installation and costs than in the case of simple use of an energy absorption element of the type in question.
Thus a need exists for an energy absorption element that provides improved security against damage due to unauthorized use or inadvertent damage and, in the process, requires little outlay on manufacturing and installation. A need also exists for an improved steering column for a motor vehicle.